The present invention relates to turning mechanisms for wheeled vehicles. The invention is specifically concerned with those turning mechanisms capable of being adapted to tandem wheeled vehicles.
Many attempts have been made in the past to incorporate turning capabilities in vehicles equipped with tandem wheels. In general, vehicles equipped with tandem wheels are incapable of turning while all the wheels are on the ground. In-line roller skates, for example, suffer from this inconvenience. Typical in-line roller skates employ an arrangement in which three to five wheels are placed in tandem. One of the biggest drawbacks of the in-line roller skate is that the operator is incapable of making right or left turns during single foot skating. Skateboards typically overcome this problem by employing a plurality of suspension frames which carry a wheel on either side, Turning is subsequently accomplished by movement of the suspension frame and not the wheels themselves. A variety of spring and tension assemblies have been employed by the prior art to control the turning of wheels in vehicles where the wheels are in tandem, but these devices are often complicated and difficult to manufacture economically. Accordingly, a simple and inexpensive turning mechanism would be beneficial for tandem wheeled vehicles.
Several designs have been proposed by the prior art to eliminate the problems associated with the turning of tandem wheeled vehicles. For example, U.S. Pat. No. 5,398,949 discloses a roller skate having a steering mechanism which allows the operator to execute figure skating maneuvers. The roller skate includes a steering cushion mechanism and a pivotal-turntable brake wheel mechanism. The steering cushion mechanism utilizes either a combination of screws and springs, or resilient members in conjunction with the axle of each wheel. In certain instances, a combination of resilient members, screws, and springs is utilized. However, the mechanism is still somewhat complicated because the frame must be designed to accommodate all of the additional parts.
U.S. Pat. No. 4,382,605 shows a steering mechanism for tandem wheeled vehicles. The mechanism includes a frame to which a pair of suspension members is attached. Two subsuspension members are also attached to the frame, one at each point of attachment of the suspension members. Each subsuspension member carries two wheels. The subsuspension members allow their respective sets of wheels to turn and follow a curved path dictated by the operator. However, the steering mechanism requires the addition of a suspension member and a subsuspension member, both of which must be attached to the base. These additional members increase the number of parts and create a more complex system.
U.S. Pat. No. 1,778,850 shows a roller skate suitable for figure skating. The roller skate includes a main wheel which is centrally positioned below the skate and a pair of auxiliary wheels, such as casters, at the front and rear positions of the skate. The auxiliary wheels are typically of smaller diameter than the main wheel and capable of swivelling. However, the auxiliary wheels are free to swivel uncontrolled, thereby creating an imprecise control system.
While the foregoing arrangements address the need for providing simple and inexpensive turning capabilities to tandem wheeled vehicles, the problem persists. Most of the prior art focuses on arrangements suitable only for roller skates and figure skating. Others are unable to adequately provide a mechanism that is simple and easy to manufacture. Consequently, it remains difficult to turn tandem wheeled vehicles.